Regulations are placing more restrictive quality demands on diesel fuels. For example, the continuing reduction of sulfur specifications in diesel fuels has placed a strain on low pressure hydrotreating units. High pressure units can require increased amounts of hydrogen to perform hydrotreatment, and attempting to retrofit a low pressure unit to handle high pressure hydroprocessing can be expensive. Currently, undercutting and high start-of-run temperatures are used to produce ultra-low-sulfur diesel in low pressure hydrotreating units, but with the corresponding difficulties of undesirable liquid yield losses and/or reduced catalyst cycle length. Higher activity hydrodesulfurization catalysts could allow an increased number of existing low pressure hydrotreatment units to still be used while achieving desired sulfur target levels, thus reducing capital investment and/or avoiding increasing burdens on the hydrogen supply in a refinery.
U.S. Pat. No. 7,951,746 and U.S. Published Patent Application No. 2010/0093522 describe catalysts developed in an attempt to provide increased activity for ultra-low sulfur processing of distillate and/or higher boiling range feeds.